Does the pre-operative serum phosphate level predict early hypocalcaemia following parathyroidectomy for primary hyperparathyroidism?

Background And Objectives: Hypocalcaemia is a significant post-operative complication following parathyroidectomy. Early identification of risk factors can help pre-empt hypocalcaemia and avoid serious sequelae. It can also help identify those patients that are not suitable for day-case surgery. The aim of this study was to analyse the predictive value of the pre-operative serum phosphate level as an indicator for developing hypocalcaemia post-operatively in patients undergoing parathyroidectomy for primary hyperparathyroidism.

Methods: We performed a retrospective review of all patients who underwent parathyroidectomy between 2008 and 2010 at the Southern General Hospital in Glasgow. Data collected included the number of parathyroid glands excised and their histology, pre-operative adjusted calcium (aCa) and phosphate levels, post-operative aCa at 6 and 24 h following surgery, and the fall in aCa levels in the first 6 h and 24 h following surgery. Minitab Statistical Analysis (Version 15) was used for data analysis.

Results: Fifty-six patients underwent parathyroidectomy in the study period. Twelve patients were excluded for various reasons including incomplete records and secondary hyperparathyroidism. Patients given calcium or Vitamin D supplements immediately post-operatively were also excluded. Statistical analysis showed no significant correlation between the pre-operative phosphate level and the post-operative decline in aCa level 6 h or 24 h following surgery.

Conclusions: Patients with a lower phosphate level pre-operatively were not at risk of a more drastic fall in calcium levels following parathyroidectomy. The pre-operative phosphate level was not found to be predictive of post-operative hypocalcaemia in our study.